Gross out?

What's Shane Bowman tossing around? His own heart! Last summer, the 12-year-old from Edmonton, Canada, received a heart transplant. And to help put closure to his illness and surgery, doctors allowed Bowman to handle his diseased heart after they replaced it.

Think the heart looks too large? Bowman suffered from dialated cardiomyopathy, a disease that caused his heart to enlarge to nearly 555 grams. "A healthy adult heart weighs about 350 grams," says Dr. Richard Stein, spokesperson for the American Heart Association. "A child's normal heart would weigh less."

A number of factors, including a virus, can cause dialated cardiomyopathy. The cavity stretches, the walls thin, and the heart gets bigger. The weakened heart doesn't pump normally; blood flows more slowly and clots easily. "Then fluids get backed up in the lungs, making it hard to breathe," says Stein. Drug treatment may help but rarely cure. In severe cases, surgery is required.

Stein considers Bowman lucky: "In the U.S., for every heart transplant performed there are 25 people or more waiting for one." And the number of available hearts continues to decline. "Things won't get better unless artificial hearts improve or people become more comfortable donating their organs."